Search: id:A060274 Results 1-1 of 1 results found. %I A060274 %S A060274 1,3,5,7,13,21,41,91,269,419,921,2983,8519,18859,53611,136631 %N A060274 Hard numbers: a(n) = smallest number m with f(m) = n, where f(m) is the smallest number of digits that are needed to construct m using only 1's, 2's and any number of +, -, *, ^ signs, not allowing concatenation of the digits. %C A060274 It seems that to obtain this sequence we need to impose the additional rule that x-y is allowed only when x-y > 0. %D A060274 C. A. Pickover, "Wonders of Numbers", Chapter 78, 'Creator Numbers', Oxford University Press, NY, 2001. pp. 187-189, 343-345. %D A060274 Ken Shirriff, University of California, personal communication. %H A060274 C. A. Pickover, "Wonders of Numbers, Adventures in Mathematics, Mind and Meaning," Zentralblatt review %e A060274 a(11)= 921 because this is the smallest number that requires 11 digits for its expression. %Y A060274 The sequence f(n) is given in A099053. Cf. A060273. %Y A060274 Sequence in context: A093326 A154700 A051507 this_sequence A005235 A107664 A085013 %Y A060274 Adjacent sequences: A060271 A060272 A060273 this_sequence A060275 A060276 A060277 %K A060274 nonn %O A060274 1,2 %A A060274 Jason Earls (zevi_35711(AT)yahoo.com), Mar 22 2001 %E A060274 Entry revised by Larry Reeves (larryr(AT)acm.org), Apr 26 2001 %E A060274 Entry improved by comments from Tim Peters (tim.one(AT)comcast.net), Nov 14 2004 Search completed in 0.001 seconds